Environmental considerations in Europe, Canada and the United States regarding the use less hazardous materials in industrial oils has obviated the need to find replacements for chlorinated paraffins (CP). Cutting fluids containing chlorine-based extreme pressure agents have been criticized as responsible for corrosion and damage of incinerators caused by environmental pollution and emission of chlorine gases, as well as the generation of dioxin during incineration of waste.
Generally speaking, in metal working processes such as cutting and grinding, chlorine-based extreme pressure agents have been used because of their excellent ability to improve cutting performance and relatively low cost.
Moreover, chlorinated paraffins, a class of chlorine-based extreme pressure agents, raise some concern about their toxicity and carcinogenicity.
As such, soluble oil emulsions with extreme pressure agents absent chlorinated paraffins are preferred. However, the ability to provide soluble oil emulsions containing overbased products has been hampered by incompatibilities of the overbased material and the soluble oil. In general, overbased materials provide hazy soluble oil base and cause phase separation and/or sediment in the final emulsion.
There are numerous references in the literature describing soluble oil formulations for forming stable emulsions with water, see e.g., U.S. Pat. Nos. 2,307,744; 2,470,913; 2,670,310; 2,695,272; 2,846,393; and 2,913,410. The compositions described in these prior art patents generally include mineral oil and an emulsifier package comprising an emulsifier, a coupling agent, and various additives. While these prior art compositions have been quite satisfactory in many instances, there has nevertheless been a continuing need for an oil soluble concentrate capable of forming a stable emulsion, particularly for use as cutting oil in machines.
There remains a need in the art for environmentally friendly stable cutting oil emulsions with improved cutting performance.